WO2010151862A1 - Process of forming a grid cathode on the front-side of a silicon wafer - Google Patents
Process of forming a grid cathode on the front-side of a silicon wafer Download PDFInfo
- Publication number
- WO2010151862A1 WO2010151862A1 PCT/US2010/040147 US2010040147W WO2010151862A1 WO 2010151862 A1 WO2010151862 A1 WO 2010151862A1 US 2010040147 W US2010040147 W US 2010040147W WO 2010151862 A1 WO2010151862 A1 WO 2010151862A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- silicon wafer
- silver
- grid cathode
- metal paste
- group
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 54
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 53
- 239000010703 silicon Substances 0.000 title claims abstract description 53
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 51
- 229910052751 metal Inorganic materials 0.000 claims abstract description 67
- 239000002184 metal Substances 0.000 claims abstract description 67
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 52
- 229910052709 silver Inorganic materials 0.000 claims abstract description 48
- 239000004332 silver Substances 0.000 claims abstract description 48
- 239000011521 glass Substances 0.000 claims abstract description 40
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 38
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 32
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000010304 firing Methods 0.000 claims abstract description 18
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 17
- 229910011255 B2O3 Inorganic materials 0.000 claims abstract description 16
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 16
- 229910052681 coesite Inorganic materials 0.000 claims abstract description 16
- 229910052906 cristobalite Inorganic materials 0.000 claims abstract description 16
- 229910052682 stishovite Inorganic materials 0.000 claims abstract description 16
- 229910052905 tridymite Inorganic materials 0.000 claims abstract description 16
- 239000000843 powder Substances 0.000 claims abstract description 15
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229910052802 copper Inorganic materials 0.000 claims abstract description 11
- 239000010949 copper Substances 0.000 claims abstract description 11
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 9
- 238000004519 manufacturing process Methods 0.000 claims abstract description 6
- YEXPOXQUZXUXJW-UHFFFAOYSA-N lead(II) oxide Inorganic materials [Pb]=O YEXPOXQUZXUXJW-UHFFFAOYSA-N 0.000 claims description 12
- 238000000151 deposition Methods 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 6
- 238000007639 printing Methods 0.000 claims description 5
- 238000007650 screen-printing Methods 0.000 claims description 4
- 229910052593 corundum Inorganic materials 0.000 abstract 1
- 229910001845 yogo sapphire Inorganic materials 0.000 abstract 1
- 235000012431 wafers Nutrition 0.000 description 30
- 239000010410 layer Substances 0.000 description 29
- 229910052782 aluminium Inorganic materials 0.000 description 24
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 24
- 239000000203 mixture Substances 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- 238000009792 diffusion process Methods 0.000 description 6
- 239000003960 organic solvent Substances 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 239000000758 substrate Substances 0.000 description 6
- 239000000470 constituent Substances 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 229910003087 TiOx Inorganic materials 0.000 description 4
- 229910052814 silicon oxide Inorganic materials 0.000 description 4
- HLLICFJUWSZHRJ-UHFFFAOYSA-N tioxidazole Chemical compound CCCOC1=CC=C2N=C(NC(=O)OC)SC2=C1 HLLICFJUWSZHRJ-UHFFFAOYSA-N 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 238000005286 illumination Methods 0.000 description 3
- 229910052809 inorganic oxide Inorganic materials 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- SVTBMSDMJJWYQN-UHFFFAOYSA-N 2-methylpentane-2,4-diol Chemical compound CC(O)CC(C)(C)O SVTBMSDMJJWYQN-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 229910004205 SiNX Inorganic materials 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- GHVNFZFCNZKVNT-UHFFFAOYSA-N decanoic acid Chemical compound CCCCCCCCCC(O)=O GHVNFZFCNZKVNT-UHFFFAOYSA-N 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- DOIRQSBPFJWKBE-UHFFFAOYSA-N dibutyl phthalate Chemical compound CCCCOC(=O)C1=CC=CC=C1C(=O)OCCCC DOIRQSBPFJWKBE-UHFFFAOYSA-N 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- POULHZVOKOAJMA-UHFFFAOYSA-N dodecanoic acid Chemical compound CCCCCCCCCCCC(O)=O POULHZVOKOAJMA-UHFFFAOYSA-N 0.000 description 2
- 239000002019 doping agent Substances 0.000 description 2
- IPCSVZSSVZVIGE-UHFFFAOYSA-N hexadecanoic acid Chemical compound CCCCCCCCCCCCCCCC(O)=O IPCSVZSSVZVIGE-UHFFFAOYSA-N 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 238000003801 milling Methods 0.000 description 2
- 229920000620 organic polymer Polymers 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 150000003376 silicon Chemical class 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- WRIDQFICGBMAFQ-UHFFFAOYSA-N (E)-8-Octadecenoic acid Natural products CCCCCCCCCC=CCCCCCCC(O)=O WRIDQFICGBMAFQ-UHFFFAOYSA-N 0.000 description 1
- WUOACPNHFRMFPN-SECBINFHSA-N (S)-(-)-alpha-terpineol Chemical compound CC1=CC[C@@H](C(C)(C)O)CC1 WUOACPNHFRMFPN-SECBINFHSA-N 0.000 description 1
- RUJPNZNXGCHGID-UHFFFAOYSA-N (Z)-beta-Terpineol Natural products CC(=C)C1CCC(C)(O)CC1 RUJPNZNXGCHGID-UHFFFAOYSA-N 0.000 description 1
- OAYXUHPQHDHDDZ-UHFFFAOYSA-N 2-(2-butoxyethoxy)ethanol Chemical compound CCCCOCCOCCO OAYXUHPQHDHDDZ-UHFFFAOYSA-N 0.000 description 1
- VXQBJTKSVGFQOL-UHFFFAOYSA-N 2-(2-butoxyethoxy)ethyl acetate Chemical compound CCCCOCCOCCOC(C)=O VXQBJTKSVGFQOL-UHFFFAOYSA-N 0.000 description 1
- TWJNQYPJQDRXPH-UHFFFAOYSA-N 2-cyanobenzohydrazide Chemical compound NNC(=O)C1=CC=CC=C1C#N TWJNQYPJQDRXPH-UHFFFAOYSA-N 0.000 description 1
- LQJBNNIYVWPHFW-UHFFFAOYSA-N 20:1omega9c fatty acid Natural products CCCCCCCCCCC=CCCCCCCCC(O)=O LQJBNNIYVWPHFW-UHFFFAOYSA-N 0.000 description 1
- QSBYPNXLFMSGKH-UHFFFAOYSA-N 9-Heptadecensaeure Natural products CCCCCCCC=CCCCCCCCC(O)=O QSBYPNXLFMSGKH-UHFFFAOYSA-N 0.000 description 1
- RSWGJHLUYNHPMX-UHFFFAOYSA-N Abietic-Saeure Natural products C12CCC(C(C)C)=CC2=CCC2C1(C)CCCC2(C)C(O)=O RSWGJHLUYNHPMX-UHFFFAOYSA-N 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 239000005632 Capric acid (CAS 334-48-5) Substances 0.000 description 1
- 229920000896 Ethulose Polymers 0.000 description 1
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 1
- 239000001859 Ethyl hydroxyethyl cellulose Substances 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 239000005639 Lauric acid Substances 0.000 description 1
- OYHQOLUKZRVURQ-HZJYTTRNSA-N Linoleic acid Chemical compound CCCCC\C=C/C\C=C/CCCCCCCC(O)=O OYHQOLUKZRVURQ-HZJYTTRNSA-N 0.000 description 1
- 235000021360 Myristic acid Nutrition 0.000 description 1
- TUNFSRHWOTWDNC-UHFFFAOYSA-N Myristic acid Natural products CCCCCCCCCCCCCC(O)=O TUNFSRHWOTWDNC-UHFFFAOYSA-N 0.000 description 1
- 239000005642 Oleic acid Substances 0.000 description 1
- ZQPPMHVWECSIRJ-UHFFFAOYSA-N Oleic acid Natural products CCCCCCCCC=CCCCCCCCC(O)=O ZQPPMHVWECSIRJ-UHFFFAOYSA-N 0.000 description 1
- 235000021314 Palmitic acid Nutrition 0.000 description 1
- KHPCPRHQVVSZAH-HUOMCSJISA-N Rosin Natural products O(C/C=C/c1ccccc1)[C@H]1[C@H](O)[C@@H](O)[C@@H](O)[C@@H](CO)O1 KHPCPRHQVVSZAH-HUOMCSJISA-N 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- 235000021355 Stearic acid Nutrition 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- OVKDFILSBMEKLT-UHFFFAOYSA-N alpha-Terpineol Natural products CC(=C)C1(O)CCC(C)=CC1 OVKDFILSBMEKLT-UHFFFAOYSA-N 0.000 description 1
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 239000006117 anti-reflective coating Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 229960002380 dibutyl phthalate Drugs 0.000 description 1
- -1 ester alcohols Chemical class 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- 235000019326 ethyl hydroxyethyl cellulose Nutrition 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229940051250 hexylene glycol Drugs 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- QXJSBBXBKPUZAA-UHFFFAOYSA-N isooleic acid Natural products CCCCCCCC=CCCCCCCCCC(O)=O QXJSBBXBKPUZAA-UHFFFAOYSA-N 0.000 description 1
- 239000003350 kerosene Substances 0.000 description 1
- 229960004232 linoleic acid Drugs 0.000 description 1
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 1
- 229910001947 lithium oxide Inorganic materials 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- WQEPLUUGTLDZJY-UHFFFAOYSA-N n-Pentadecanoic acid Natural products CCCCCCCCCCCCCCC(O)=O WQEPLUUGTLDZJY-UHFFFAOYSA-N 0.000 description 1
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 1
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 1
- ZQPPMHVWECSIRJ-KTKRTIGZSA-N oleic acid Chemical compound CCCCCCCC\C=C/CCCCCCCC(O)=O ZQPPMHVWECSIRJ-KTKRTIGZSA-N 0.000 description 1
- 239000006259 organic additive Substances 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 239000003791 organic solvent mixture Substances 0.000 description 1
- 150000002902 organometallic compounds Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 229920001568 phenolic resin Polymers 0.000 description 1
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 1
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 1
- 229920000193 polymethacrylate Polymers 0.000 description 1
- 159000000001 potassium salts Chemical class 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 238000005476 soldering Methods 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000008117 stearic acid Substances 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- QJVXKWHHAMZTBY-GCPOEHJPSA-N syringin Chemical compound COC1=CC(\C=C\CO)=CC(OC)=C1O[C@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 QJVXKWHHAMZTBY-GCPOEHJPSA-N 0.000 description 1
- 150000003505 terpenes Chemical class 0.000 description 1
- 235000007586 terpenes Nutrition 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- KHPCPRHQVVSZAH-UHFFFAOYSA-N trans-cinnamyl beta-D-glucopyranoside Natural products OC1C(O)C(O)C(CO)OC1OCC=CC1=CC=CC=C1 KHPCPRHQVVSZAH-UHFFFAOYSA-N 0.000 description 1
- 239000011345 viscous material Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/14—Conductive material dispersed in non-conductive inorganic material
- H01B1/16—Conductive material dispersed in non-conductive inorganic material the conductive material comprising metals or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/062—Glass compositions containing silica with less than 40% silica by weight
- C03C3/07—Glass compositions containing silica with less than 40% silica by weight containing lead
- C03C3/072—Glass compositions containing silica with less than 40% silica by weight containing lead containing boron
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
- C03C8/02—Frit compositions, i.e. in a powdered or comminuted form
- C03C8/10—Frit compositions, i.e. in a powdered or comminuted form containing lead
- C03C8/12—Frit compositions, i.e. in a powdered or comminuted form containing lead containing titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
- C03C8/14—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions
- C03C8/18—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions containing free metals
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Geochemistry & Mineralogy (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Inorganic Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Manufacturing & Machinery (AREA)
- Photovoltaic Devices (AREA)
- Conductive Materials (AREA)
- Manufacturing Of Electric Cables (AREA)
- Glass Compositions (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
Abstract
A process for the production of a grid cathode on the front-side of a silicon wafer by applying and firing a metal paste on the silicon wafer in a front-side grid electrode pattern to form a seed grid cathode and subsequently subjecting the silicon wafer to a LIP process, wherein the metal paste comprises an organic vehicle and an inorganic content comprising (a) 90 to 98 wt.-% of at least one electrically conductive metal powder selected from the group consisting of nickel, copper and silver, and (b) 0.25 to 8 wt.-% of at least one glass frit selected from the group consisting of glass frits containing 47.5 to 64.3 wt.-% of PbO, 23.8 to 32.2 wt.-% of SiO2, 3.9 to 5.4 wt.-% of Al2O3, 2.8 to 3.8 wt.-% of TiO2 and 6.9 to 9.3 wt.-% of B2O3.
Description
TITLE
PROCESS OF FORMING A GRID CATHODE ON THE FRONT-SIDE OF
A SILICON WAFER
FIELD OF THE INVENTION
The present invention is directed to a process of forming a grid cathode on the front-side of a silicon wafer.
TECHNICAL BACKGROUND OF THE INVENTION A conventional solar cell structure with a p-type base has a negative electrode that is typically on the front-side or illuminated side of the cell and a positive electrode on the back-side. It is well known that radiation of an appropriate wavelength falling on a p-n junction of a semiconductor body serves as a source of external energy to generate electron-hole pairs in that body. The potential difference that exists at a p- n junction, causes holes and electrons to move across the junction in opposite directions, thereby giving rise to flow of an electric current that is capable of delivering power to an external circuit. Most solar cells are in the form of a silicon wafer that has been metallized, i.e., provided with metal contacts which are electrically conductive.
Most electric power-generating solar cells currently used are silicon solar cells. Electrodes in particular are made by using a method such as screen printing from metal pastes.
The production of a silicon solar cell typically starts with a p-type silicon substrate in the form of a silicon wafer on which an n-type diffusion layer of the reverse conductivity type is formed by the thermal diffusion of phosphorus (P) or the like. Phosphorus oxychlohde (POCI3) is commonly used as the gaseous phosphorus diffusion source, other liquid sources are phosphoric acid and the like. In the absence of any particular modification, the diffusion layer is formed over the entire surface of the silicon substrate. The p-n junction is formed where the concentration of the p-type dopant equals the concentration of the n-type dopant;
conventional cells that have the p-n junction close to the illuminated side, have a junction depth between 0.05 and 0.5 μm.
After formation of this diffusion layer excess surface glass is removed from the rest of the surfaces by etching with an acid such as hydrofluoric acid.
Next, an ARC layer (antireflective coating layer) Of TiOx, SiOx, TiOx/SiOx, or, in particular, SiNx or SisN4 is formed on the n-type diffusion layer to a thickness of between 0.05 and 0.1 μm by a process, such as, for example, plasma CVD (chemical vapor deposition). A conventional solar cell structure with a p-type base typically has a negative grid electrode on the front-side of the cell and a positive electrode on the back-side. The grid electrode is typically applied by screen printing and drying a front-side silver paste (front electrode forming silver paste) on the ARC layer on the front-side of the cell. The front-side grid electrode is typically screen printed in a so-called H pattern which comprises (i) thin parallel finger lines (collector lines) and (ii) two busbars intersecting the finger lines at right angle. In addition, a back-side silver or silver/aluminum paste and an aluminum paste are screen printed (or some other application method) and successively dried on the back-side of the substrate. Normally, the back-side silver or silver/aluminum paste is screen printed onto the silicon wafer's back-side first as two parallel busbars or as rectangles (tabs) ready for soldering interconnection strings (presoldered copper ribbons). The aluminum paste is then printed in the bare areas with a slight overlap over the back-side silver or silver/aluminum. In some cases, the silver or silver/aluminum paste is printed after the aluminum paste has been printed. Firing is then typically carried out in a belt furnace for a period of 1 to 5 minutes with the wafer reaching a peak temperature in the range of 700 to 9000C. The front grid electrode and the back electrodes can be fired sequentially or cofired. The aluminum paste is generally screen printed and dried on the back-side of the silicon wafer. The wafer is fired at a temperature above the melting point of aluminum to form an aluminum-silicon melt, subsequently, during the cooling phase, an epitaxially grown layer of silicon is formed that is doped with aluminum. This layer is generally
called the back surface field (BSF) layer. The aluminum paste is transformed by firing from a dried state to an aluminum back electrode. The back-side silver or silver/aluminum paste is fired at the same time, becoming a silver or silver/aluminum back electrode. During firing, the boundary between the back-side aluminum and the back-side silver or silver/aluminum assumes an alloy state, and is connected electrically as well. The aluminum electrode accounts for most areas of the back electrode, owing in part to the need to form a p+ layer. A silver or silver/aluminum back electrode is formed over portions of the back-side (often as 2 to 6 mm wide busbars) as an electrode for interconnecting solar cells by means of pre-soldered copper ribbon or the like. In addition, the front-side silver paste printed as front-side grid electrode sinters and penetrates through the ARC layer during firing, and is thereby able to electrically contact the n-type layer. This type of process is generally called "firing through".
The electrical efficiency of a silicon solar cell of the type described above can be increased by employing a so-called LIP (light-induced plating) process by which electrically conductive silver is deposited on the front-side grid electrode. During the LIP process the front-side grid electrode serves as a seed electrode which is electroplated with silver; see A. Mette et al., "Increasing the Efficiency of Screen-Printed Silicon Solar Cells by Light-Induced Silver Plating", Photovoltaic Energy Conversion, Conference Record of the 2006 IEEE 4th World Conference on Volume 1 , May 2006, pages 1056 - 1059. During the LIP process a silicon solar cell provided with a front-side seed grid cathode is immersed in a LIP bath, i.e. in an aqueous bath containing silver in cathodically depositable form. The front-side of the cell is illuminated and the negative potential created on the front-side causes silver to deposit on the seed grid cathode. At the same time the back-side of the cell is connected to an external power supply and a voltage bias is applied for compensating the positive potential created under illumination of the silicon wafer's front-side to prevent dissolution of the aluminum layer. A sacrificial electrode of silver is anodically connected to the external power supply for replenishing the
LIP bath with the silver consumed from the LIP bath by the deposition process.
It has now been found that the electrical efficiency of a silicon solar cell provided with a front-side grid cathode made by applying and firing a seed grid cathode and depositing silver by LIP thereon can be further improved when the electrically conductive metal paste used for applying the seed grid cathode contains glass frit having a certain composition.
SUMMARY OF THE INVENTION The present invention relates to a process for the production of a grid cathode on the front-side of a silicon wafer having a p-type region, an n-type region, a p-n junction and an ARC layer on said front-side, comprising the steps: (1 ) providing a silicon wafer having an ARC layer on its front-side, (2) applying and drying a metal paste on the ARC layer on the front-side of the silicon wafer in a front-side grid electrode pattern, and
(3) firing the metal paste to form a seed grid cathode, and
(4) depositing silver on the seed grid cathode by subjecting the silicon wafer provided with the seed grid cathode to a LIP process, wherein the metal paste comprises an organic vehicle and an inorganic content comprising (a) 90 to 98 wt.-% of at least one electrically conductive metal powder selected from the group consisting of nickel, copper and silver, and (b) 0.25 to 8 wt.-% of at least one glass frit selected from the group consisting of glass frits containing 47.5 to 64.3 wt.-% of PbO, 23.8 to 32.2 wt.-% of SiO2, 3.9 to 5.4 wt.-% of AI2O3, 2.8 to 3.8 wt.-% of TiO2 and 6.9 to 9.3 wt.-% of B2O3.
In the description and the claims the terms "seed grid cathode" and "grid cathode" are used to draw a clear distinction between the seed grid cathode obtained on completion of process step (3) and the grid cathode obtained on completion of process step (4), i.e. the grid cathode produced by the process of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
In step (1 ) of the process of the present invention a silicon wafer having an ARC layer on its front-side is provided. The silicon wafer is a conventional mono- or polycrystalline silicon wafer as is conventionally used for the production of silicon solar cells; it has a p-type region, an n- type region and a p-n junction. The silicon wafer has an ARC layer, for example, Of TiOx, SiOx, TiOx/SiOx, or, in particular, SiNx or Si3N4 on its front-side. Such silicon wafers are well known to the skilled person; for brevity reasons reference is made to the section "TECHNICAL BACKGROUND OF THE INVENTION". The silicon wafer may already be provided with the conventional back-side metallizations, i.e. with a backside aluminum paste and a back-side silver or back-side silver/aluminum paste as described above in the section "TECHNICAL BACKGROUND OF THE INVENTION". Application of the back-side metal pastes (including the back-side aluminum paste) may be carried out before or after the front- side seed grid cathode is finished in step (3). Preferentially, the back-side metal pastes (including the back-side aluminum paste) are applied and fired before process step (4) is carried out. The back-side metal pastes (including the back-side aluminum paste) may be individually fired or cofired or even be cofired with the front-side metal paste applied on the ARC layer in step (2).
In step (2) of the process of the present invention a metal paste is applied on the ARC layer on the front-side of the silicon wafer in a front- side grid electrode pattern. The metal paste is a thick film conductive composition with fire- through capability, i.e. it fires through an ARC layer making electrical contact with the surface of the silicon substrate.
The metal paste comprises an organic vehicle and an inorganic content comprising (a) 90 to 98 wt.-% of at least one electrically conductive metal powder selected from the group consisting of nickel, copper and silver, and (b) 0.25 to 8 wt.-% of at least one glass frit selected from the group consisting of glass frits containing 47.5 to 64.3 wt.-% of PbO, 23.8 to 32.2 wt.-% of SiO2, 3.9 to 5.4 wt.-% Of AI2O3, 2.8 to 3.8 wt.-% of TiO2 and 6.9 to 9.3 wt.-% of B2O3.
The metal paste comprises an organic vehicle. A wide variety of inert viscous materials can be used as organic vehicle. The organic vehicle may be one in which the particulate constituents (electrically conductive metal powder, glass frit, optionally present other particulate inorganic components) are dispersible with an adequate degree of stability. The properties, in particular, the rheological properties, of the organic vehicle may be such that they lend good application properties to the metal paste, including: stable dispersion of insoluble solids, appropriate viscosity and thixotropy for the application, appropriate wettability of the ARC layer on the front-side of the silicon wafer and of the paste solids, a good drying rate, and good firing properties. The organic vehicle used in the metal paste may be a nonaqueous inert liquid. The organic vehicle may be an organic solvent or an organic solvent mixture; in an embodiment, the organic vehicle may be a solution of organic polymer(s) in organic solvent(s). Use can be made of any of various organic vehicles, which may or may not contain thickeners, stabilizers and/or other common additives. In an embodiment, the polymer used as constituent of the organic vehicle may be ethyl cellulose. Other examples of polymers which may be used alone or in combination include ethyl hydroxyethyl cellulose, wood rosin, phenolic resins and poly(meth)acrylates of lower alcohols. Examples of suitable organic solvents comprise ester alcohols and terpenes such as alpha- or beta-terpineol or mixtures thereof with other solvents such as kerosene, dibutylphthalate, diethylene glycol butyl ether, diethylene glycol butyl ether acetate, hexylene glycol and high boiling alcohols. In addition, volatile organic solvents for promoting rapid hardening after application of the metal paste can be included in the organic vehicle. Various combinations of these and other solvents may be formulated to obtain the viscosity and volatility requirements desired. The ratio of organic vehicle in the metal paste to the inorganic content (inorganic components; electrically conductive metal powder plus glass frit plus optionally present other inorganic additives) is dependent on the application method of the metal paste and the kind of organic vehicle
used, and it can vary. Usually, the metal paste will contain 40 to 95 wt.-% of inorganic components and 5 to 60 wt.-% of organic vehicle.
The inorganic content of the metal paste comprises (a) 90 to 98 wt.- % of at least one electrically conductive metal powder selected from the group consisting of nickel, copper and silver, and (b) 0.25 to 8 wt.-% of at least one glass frit selected from the group consisting of glass frits containing 47.5 to 64.3 wt.-% of PbO, 23.8 to 32.2 wt.-% of SiO2, 3.9 to 5.4 wt.-% Of AI2O3, 2.8 to 3.8 wt.-% Of TiO2 and 6.9 to 9.3 wt.-% of B2O3.
In an embodiment, the inorganic content of the metal paste comprises (a) 92 to 98 wt.-% of at least one electrically conductive metal powder selected from the group consisting of nickel, copper and silver, and (b) 1.5 to 4 wt.-% of at least one glass frit selected from the group consisting of glass frits containing 47.5 to 64.3 wt.-% of PbO, 23.8 to 32.2 wt.-% of SiO2, 3.9 to 5.4 wt.-% of AI2O3, 2.8 to 3.8 wt.-% of TiO2 and 6.9 to 9.3 wt.-% of B2O3.
It is possible that the inorganic content of the metal paste comprises further inorganic components other than components (a) and (b), as can be calculated from the weight percentages of components (a) and (b). Examples of such other inorganic components comprise solid inorganic oxides or compounds capable of forming solid inorganic oxides during firing of the metal paste. Examples of said solid inorganic oxides include silicon dioxide, zinc oxide, magnesium oxide, calcium oxide and lithium oxide. In general, the inorganic content of the metal paste comprises no other glass frit than the at least one glass frit selected from the group consisting of glass frits containing 47.5 to 64.3 wt.-% of PbO, 23.8 to 32.2 wt.-% of SiO2, 3.9 to 5.4 wt.-% Of AI2O3, 2.8 to 3.8 wt.-% of TiO2 and 6.9 to 9.3 wt.-% of B2O3.
The metal paste comprises at least one electrically conductive metal powder selected from the group consisting of silver, copper and nickel. Silver powder is preferred. The metal or silver powder may be uncoated or at least partially coated with a surfactant. The surfactant may be selected from, but is not limited to, stearic acid, palmitic acid, lauric
acid, oleic acid, capric acid, myristic acid and linolic acid and salts thereof, for example, ammonium, sodium or potassium salts.
The average particle size of the electrically conductive metal powder or, in particular, silver powder is in the range of, for example, 0.2 to 5 μm.
In the description and the claims the term "average particle size" is used. It means the mean particle diameter (d50) determined by means of laser scattering. All statements made in the present description and the claims in relation to average particle sizes relate to average particle sizes of the relevant materials as are present in the metal paste.
In general the metal paste comprises only the at least one electrically conductive metal powder selected from the group consisting of silver, copper, and nickel. However, it is possible to replace a small proportion of the electrically conductive metal selected from the group consisting of silver, copper and nickel by one or more other particulate metals. The proportion of such other particulate metal(s) is, for example, 0 to 10 wt.%, based on the total of particulate metals contained in the metal paste.
As already mentioned, the metal paste comprises at least one glass frit as inorganic binder. The one or more glass frits are selected from the group consisting of glass frits containing 47.5 to 64.3 wt.-% of PbO, 23.8 to 32.2 wt.-% of SiO2, 3.9 to 5.4 wt.-% of AI2O3, 2.8 to 3.8 wt.-% of TiO2 and 6.9 to 9.3 wt.-% of B2O3. In an embodiment, the one or more glass frits are selected from the group consisting of glass frits containing 50.3 to 61.5 wt.-% of PbO, 25.2 to 30.8 wt.-% of SiO2, 4.2 to 5.2 wt.-% of AI2O3, 3.0 to 3.6 wt.-% of TiO2 and 7.3 to 8.9 wt.-% of B2O3. In another embodiment, the one or more glass frits are selected from the group consisting of glass frits containing 53.1 to 58.7 wt.-% of PbO, 26.6 to 29.4 wt.-% of SiO2, 4.5 to 4.9 wt.-% Of AI2O3, 3.1 to 3.5 wt.-% of TiO2 and 7.7 to 8.5 wt. -% of B2O3. As can be calculated from the weight percentages of PbO, SiO2, AI2O3, TiO2 and B2O3, the latter do not necessarily add up to 100 wt.-%; however, in an embodiment, the total of the weight percentages of PbO, SiO2, AI2O3, TiO2 and B2O3 is 100 wt.-%. In case the
weight percentages of PbO, SiO2, AI2O3, TiO2 and B2O3 do not total 100 wt.-%, the missing wt.-% may in particular be contributed by one or more other oxides.
The average particle size of the at least one glass frit is in the range of, for example, 0.5 to 4 μm.
The preparation of the glass frit is well known and consists, for example, in melting together the constituents of the glass in the form of the oxides of the constituents and pouring such molten composition into water to form the frit. As is well known in the art, heating may be conducted to a peak temperature of, for example, 1300 to 1450 0C and for a time such that the melt becomes entirely liquid and homogeneous, for example, 0.5 to 1.5 hours.
The glass may be milled in a ball mill with water or inert low viscosity, low boiling point organic liquid to reduce the particle size of the frit and to obtain a frit of substantially uniform size. It may then be settled in water or said organic liquid to separate fines and the supernatant fluid containing the fines may be removed. Other methods of classification may be used as well.
The metal paste is a viscous composition, which may be prepared by mechanically mixing the electrically conductive metal powder and the glass frit and the other optionally present solid inorganic components with the organic vehicle. In an embodiment, the manufacturing method power mixing, a dispersion technique that is equivalent to the traditional roll milling, may be used; roll milling or other mixing technique can also be used.
The metal paste can be used as such or may be diluted, for example, by the addition of additional organic solvent(s); accordingly, the weight percentage of all the other constituents of the metal paste may be decreased. In step (2) of the process of the present invention the metal paste is applied on the ARC layer on the front-side of the silicon wafer in a front- side grid electrode pattern. Examples of metal paste application methods
include pen-writing and printing methods, such as, for example, jet printing, stencil printing and screen printing. The front-side grid electrode may comprise (i) thin parallel finger lines and (ii) two or more parallel busbars intersecting the finger lines at right angle. In an embodiment, the grid pattern is an H pattern with two parallel busbars. The parallel finger lines may have a distance between each other of, for example, 2 to 5 mm, a dry layer thickness of, for example, 3 to 30 μm and a width of, for example, 40 to 200 μm. The busbars may have a dry layer thickness of, for example, 10 to 50 μm and a width of, for example, 1 to 3 mm. After its application, the metal paste is dried, for example, for a period of 1 to 100 minutes with the silicon wafer reaching a peak temperature in the range of 100 to 300 0C. Drying can be carried out making use of, for example, belt, rotary or stationary driers, in particular, IR (infrared) belt driers. In step (3) of the process of the present invention the dried metal paste is fired to form a seed grid cathode. The firing of step (3) may be performed, for example, for a period of 1 to 5 minutes with the silicon wafer reaching a peak temperature in the range of 700 to 900 0C. The firing can be carried out making use of, for example, single or multi-zone belt furnaces, in particular, multi-zone IR belt furnaces. The firing may happen in an inert gas atmosphere or in the presence of oxygen, for example, in the presence of air. During firing the organic substance including non-volatile organic material and the organic portion not evaporated during the drying may be removed, i.e. burned and/or carbonized, in particular, burned. The organic substance removed during firing includes organic solvent(s), optionally present organic polymer(s), optionally present organic additive(s) and organic moieties of optionally present metal-organic compounds. There is a further process taking place during firing, namely sintering of the glass frit with the electrically conductive metal powder. The metal paste etches the ARC layer and fires through making electrical contact with the silicon substrate.
As already mentioned, firing may be performed as so-called cofiring together with back-side metal pastes that have been applied to the silicon wafer.
The seed grid cathode so formed in step (3) of the process of the present invention is electrically conductive and allows for successfully performing subsequent process step (4); i.e. the seed grid cathode can be electroplated with silver during process step (4) to form the front-side grid cathode.
In step (4) of the process of the present invention the silicon wafer provided with the seed grid cathode is subjected to a LIP process thereby depositing silver on the seed grid cathode. To this end the silicon wafer is immersed into a LIP bath and the front-side of the immersed silicon wafer with the seed grid cathode thereon is illuminated. Regarding the connection of the silicon wafer's back-side to an external power supply and the measures taken to keep the LIP bath's silver content constant, reference is made to the section "TECHNICAL BACKGROUND OF THE INVENTION". The LIP bath is an aqueous bath containing silver in cathodically depositable form. Typically, the LIP bath has an alkaline pH (measured by making use of a conventional pH meter) in the range of, for example, 8 to 11 , in particular, 9 to 10.5. For example, halogen or fluorescent lamps may be used for illumination purposes. The illumination is carried out, until the desired amount of silver has been deposited from the LIP bath on the seed grid cathode, i.e. until the grid cathode has been formed. During this step (4) of the process of the invention the silver deposition results in growth of the grid obtained in step (3); for example, in case of a grid comprising parallel finger lines and two or more parallel busbars intersecting the finger lines at right angle, the layer thickness of the fingers may increase by, for example, 5 to 30 μm, their width by, for example, 10 to 100 μm and the layer thickness of the busbars by, for example, 5 to 30 μm. The growth of the busbars in width is hardly worth mentioning given their starting width of, for example, 1 to 3 mm.
After the LIP process has been finished, the silicon wafer provided with the front-side grid cathode is removed from the LIP bath, rinsed with water to remove LIP bath residues and dried.
The aforementioned further improvement of the electrical efficiency of silicon solar cells provided with a front-side grid cathode made by the process of the present invention is not simply a result of carrying out the
LIP process step (4). Without being bound by theory and although not investigated in sufficient detail, it is believed that the composition of the glass frit contained in the metal paste used for the application of the front- side seed grid cathode is key. It is believed that said glass frit composition allows for a well-balanced ratio between the deposition of silver and dissolution of glass during the LIP process step (4) with the result of forming a grid cathode with a comparably dense structure with good electrical conductivity and low contact resistance with the silicon substrate.
Claims
1. A process for the production of a grid cathode on the front-side of a silicon wafer having a p-type region, an n-type region, a p-n junction and an ARC layer on said front-side, comprising the steps:
(1 ) providing a silicon wafer having an ARC layer on its front-side,
(2) applying and drying a metal paste on the ARC layer on the front-side of the silicon wafer in a front-side grid electrode pattern, and
(3) firing the metal paste to form a seed grid cathode, and
(4) depositing silver on the seed grid cathode by subjecting the silicon wafer provided with the seed grid cathode to a LIP process, wherein the metal paste comprises an organic vehicle and an inorganic content comprising (a) 90 to 98 wt.-% of at least one electrically conductive metal powder selected from the group consisting of nickel, copper and silver, and (b) 0.25 to 8 wt.-% of at least one glass frit selected from the group consisting of glass frits containing 47.5 to 64.3 wt.-% of PbO, 23.8 to 32.2 wt.-% of SiO2, 3.9 to 5.4 wt.-% Of AI2O3, 2.8 to 3.8 wt.-% of TiO2 and 6.9 to 9.3 wt.-% of B2O3.
2. The process of claim 1 , wherein the at least one glass frit is selected from the group consisting of glass frits containing 50.3 to 61.5 wt.-% of PbO, 25.2 to 30.8 wt.-% of SiO2, 4.2 to 5.2 wt.-% Of AI2O3, 3.0 to 3.6 wt.-% of TiO2 and 7.3 to 8.9 wt.-% of B2O3.
3. The process of claim 1 , wherein the at least one glass frit is selected from the group consisting of glass frits containing 53.1 to 58.7 wt.-% of PbO, 26.6 to 29.4 wt.-% of SiO2, 4.5 to 4.9 wt.-% Of AI2O3, 3.1 to 3.5 wt.-% of TiO2 and 7.7 to 8.5 wt.-% of B2O3.
4. The process of any one of the preceding claims, wherein the total of the weight percentages of PbO, SiO2, AI2O3, TiO2 and B2O3 is 100 wt.-%.
5. The process of any one of the preceding claims, wherein the inorganic content comprises (a) 92 to 98 wt.-% of the at least one electrically conductive metal powder and (b) 1.5 to 4 wt.-% of the at least one glass frit.
6. The process of any one of the preceding claims, wherein the at least one electrically conductive metal powder is silver powder.
7. The process of any one of the preceding claims, wherein the metal paste contains 40 to 95 wt.-% of inorganic components and 5 to 60 wt.-% of organic vehicle.
8. The process of any one of the preceding claims, wherein the metal paste is applied by a method selected from the group consisting of pen- writing, jet printing, stencil printing and screen printing.
9. The process of any one of the preceding claims, wherein the front- side grid electrode pattern comprises (i) thin parallel finger lines and (ii) two or more parallel busbars intersecting the finger lines at right angle.
10. The process of any one of the preceding claims, wherein the LIP process comprises immersing the silicon wafer into a LIP bath and illuminating the front-side of the immersed silicon wafer with the seed grid cathode thereon.
11. The process of any one of the preceding claims, wherein the LIP bath is an aqueous bath having a pH of 8 to 11 and containing silver in cathodically depositable form.
12. A front-side grid cathode produced according to the process of any one of the preceding claims.
13. A silicon solar cell comprising a silicon wafer having an ARC layer on its front-side and the front-side grid cathode of claim 12.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010800264457A CN102804389A (en) | 2009-06-26 | 2010-06-28 | Process of forming a grid cathode on the front-side of a silicon wafer |
| EP10727637A EP2446479A1 (en) | 2009-06-26 | 2010-06-28 | Process of forming a grid cathode on the front-side of a silicon wafer |
| JP2012517820A JP2012531752A (en) | 2009-06-26 | 2010-06-28 | Method for forming grid cathode on front surface of silicon wafer |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US22063309P | 2009-06-26 | 2009-06-26 | |
| US61/220,633 | 2009-06-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2010151862A1 true WO2010151862A1 (en) | 2010-12-29 |
Family
ID=42711857
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US2010/040147 WO2010151862A1 (en) | 2009-06-26 | 2010-06-28 | Process of forming a grid cathode on the front-side of a silicon wafer |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US20110146781A1 (en) |
| EP (1) | EP2446479A1 (en) |
| JP (1) | JP2012531752A (en) |
| KR (1) | KR20120031084A (en) |
| CN (1) | CN102804389A (en) |
| WO (1) | WO2010151862A1 (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9012766B2 (en) | 2009-11-12 | 2015-04-21 | Silevo, Inc. | Aluminum grid as backside conductor on epitaxial silicon thin film solar cells |
| US9214576B2 (en) | 2010-06-09 | 2015-12-15 | Solarcity Corporation | Transparent conducting oxide for photovoltaic devices |
| US9773928B2 (en) * | 2010-09-10 | 2017-09-26 | Tesla, Inc. | Solar cell with electroplated metal grid |
| US9800053B2 (en) | 2010-10-08 | 2017-10-24 | Tesla, Inc. | Solar panels with integrated cell-level MPPT devices |
| US20140102523A1 (en) * | 2011-04-07 | 2014-04-17 | Newsouth Innovations Pty Limited | Hybrid solar cell contact |
| US9054256B2 (en) | 2011-06-02 | 2015-06-09 | Solarcity Corporation | Tunneling-junction solar cell with copper grid for concentrated photovoltaic application |
| WO2014055781A1 (en) | 2012-10-04 | 2014-04-10 | Silevo, Inc. | Photovoltaic devices with electroplated metal grids |
| US9865754B2 (en) | 2012-10-10 | 2018-01-09 | Tesla, Inc. | Hole collectors for silicon photovoltaic cells |
| CN103022261B (en) * | 2012-12-28 | 2016-07-06 | 英利能源（中国）有限公司 | Make the method and system of solaode |
| US9281436B2 (en) | 2012-12-28 | 2016-03-08 | Solarcity Corporation | Radio-frequency sputtering system with rotary target for fabricating solar cells |
| US9412884B2 (en) | 2013-01-11 | 2016-08-09 | Solarcity Corporation | Module fabrication of solar cells with low resistivity electrodes |
| US9219174B2 (en) | 2013-01-11 | 2015-12-22 | Solarcity Corporation | Module fabrication of solar cells with low resistivity electrodes |
| US10074755B2 (en) | 2013-01-11 | 2018-09-11 | Tesla, Inc. | High efficiency solar panel |
| US9624595B2 (en) | 2013-05-24 | 2017-04-18 | Solarcity Corporation | Electroplating apparatus with improved throughput |
| US10309012B2 (en) | 2014-07-03 | 2019-06-04 | Tesla, Inc. | Wafer carrier for reducing contamination from carbon particles and outgassing |
| US9899546B2 (en) | 2014-12-05 | 2018-02-20 | Tesla, Inc. | Photovoltaic cells with electrodes adapted to house conductive paste |
| US9947822B2 (en) | 2015-02-02 | 2018-04-17 | Tesla, Inc. | Bifacial photovoltaic module using heterojunction solar cells |
| US9761744B2 (en) | 2015-10-22 | 2017-09-12 | Tesla, Inc. | System and method for manufacturing photovoltaic structures with a metal seed layer |
| US9842956B2 (en) | 2015-12-21 | 2017-12-12 | Tesla, Inc. | System and method for mass-production of high-efficiency photovoltaic structures |
| US9496429B1 (en) | 2015-12-30 | 2016-11-15 | Solarcity Corporation | System and method for tin plating metal electrodes |
| US10115838B2 (en) | 2016-04-19 | 2018-10-30 | Tesla, Inc. | Photovoltaic structures with interlocking busbars |
| US10672919B2 (en) | 2017-09-19 | 2020-06-02 | Tesla, Inc. | Moisture-resistant solar cells for solar roof tiles |
| US11190128B2 (en) | 2018-02-27 | 2021-11-30 | Tesla, Inc. | Parallel-connected solar roof tile modules |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1713095A2 (en) * | 2005-04-14 | 2006-10-18 | E.I. Dupont De Nemours And Company | Method of manufacture of semiconductor device and conductive compositions used therein |
| WO2009029738A1 (en) * | 2007-08-31 | 2009-03-05 | Ferro Corporation | Layered contact structure for solar cells |
| US20090120497A1 (en) * | 2007-11-09 | 2009-05-14 | Schetty Iii Robert A | Method of metallizing solar cell conductors by electroplating with minimal attack on underlying materials of construction |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080035489A1 (en) * | 2006-06-05 | 2008-02-14 | Rohm And Haas Electronic Materials Llc | Plating process |
-
2010
- 2010-06-24 US US12/822,466 patent/US20110146781A1/en not_active Abandoned
- 2010-06-28 JP JP2012517820A patent/JP2012531752A/en active Pending
- 2010-06-28 WO PCT/US2010/040147 patent/WO2010151862A1/en active Application Filing
- 2010-06-28 KR KR1020127001908A patent/KR20120031084A/en not_active Application Discontinuation
- 2010-06-28 CN CN2010800264457A patent/CN102804389A/en active Pending
- 2010-06-28 EP EP10727637A patent/EP2446479A1/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1713095A2 (en) * | 2005-04-14 | 2006-10-18 | E.I. Dupont De Nemours And Company | Method of manufacture of semiconductor device and conductive compositions used therein |
| WO2009029738A1 (en) * | 2007-08-31 | 2009-03-05 | Ferro Corporation | Layered contact structure for solar cells |
| US20090120497A1 (en) * | 2007-11-09 | 2009-05-14 | Schetty Iii Robert A | Method of metallizing solar cell conductors by electroplating with minimal attack on underlying materials of construction |
Non-Patent Citations (2)
| Title |
|---|
| A. METTE ET AL.: "Increasing the Efficiency of Screen-Printed Silicon Solar Cells by Light-Induced Silver Plating", PHOTOVOLTAIC ENERGY CONVERSION, CONFERENCE RECORD OF THE 2006 IEEE 4TH WORLD CONFERENCE, vol. 1, May 2006 (2006-05-01), pages 1056 - 1059 |
| ZHANG Y ET AL: "Thermal properties of glass frit and effects on Si solar cells", MATERIALS CHEMISTRY AND PHYSICS, ELSEVIER, SWITZERLAND, TAIWAN, REPUBLIC OF CHINA LNKD- DOI:10.1016/J.MATCHEMPHYS.2008.09.011, vol. 114, no. 1, 15 March 2009 (2009-03-15), pages 319 - 322, XP025767791, ISSN: 0254-0584, [retrieved on 20081104] * |
Also Published As
| Publication number | Publication date |
|---|---|
| EP2446479A1 (en) | 2012-05-02 |
| JP2012531752A (en) | 2012-12-10 |
| CN102804389A (en) | 2012-11-28 |
| US20110146781A1 (en) | 2011-06-23 |
| KR20120031084A (en) | 2012-03-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US20110146781A1 (en) | Process of forming a grid cathode on the front-side of a silicon wafer | |
| US20100243048A1 (en) | Metal pastes and use thereof in the production of silicon solar cells | |
| KR101322142B1 (en) | Process of forming a grid electrode on the front-side of a silicon wafer | |
| WO2010135496A1 (en) | Process of forming a grid electrode on the front-side of a silicon wafer | |
| EP2504843A1 (en) | Process for the formation of a silver back electrode of a passivated emitter and rear contact silicon solar cell | |
| WO2010124161A1 (en) | Metal pastes and use thereof in the production of positive electrodes on p-type silicon surfaces | |
| US20110240124A1 (en) | Metal pastes and use thereof in the production of silicon solar cells | |
| WO2011097606A2 (en) | Process for the production of a mwt silicon solar cell | |
| US20130056060A1 (en) | Process for the production of lfc-perc silicon solar cells | |
| WO2013023169A1 (en) | Aluminium paste with no or poor fire -through capability and use thereof for back electrodes of passivated emitter and rear contact silicon solar cells | |
| EP2417608A1 (en) | Metal pastes and use thereof in the production of silicon solar cells | |
| KR101322149B1 (en) | Process of forming a grid electrode on the front-side of a silicon wafer | |
| US20130061918A1 (en) | Process for the formation of a silver back electrode of a passivated emitter and rear contact silicon solar cell | |
| US20110088769A1 (en) | Process of forming an electrode on the front-side of a non-textured silicon wafer | |
| US20120160314A1 (en) | Process for the formation of a silver back anode of a silicon solar cell | |
| WO2012129575A1 (en) | Process for the production of a mwt silicon solar cell | |
| US9076919B2 (en) | Process of forming an aluminum p-doped surface region of a semiconductor substrate | |
| TW201201223A (en) | Process of forming a grid cathode on the front-side of a silicon wafer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WWE | Wipo information: entry into national phase |
Ref document number: 201080026445.7 Country of ref document: CN |
|
| 121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 10727637 Country of ref document: EP Kind code of ref document: A1 |
|
| WWE | Wipo information: entry into national phase |
Ref document number: 2010727637 Country of ref document: EP |
|
| WWE | Wipo information: entry into national phase |
Ref document number: 2012517820 Country of ref document: JP |
|
| NENP | Non-entry into the national phase |
Ref country code: DE |
|
| ENP | Entry into the national phase |
Ref document number: 20127001908 Country of ref document: KR Kind code of ref document: A |